Method of making upset seamless tubing



y 1941- s. 'E. DIESCHER 2,241,083

METHOD OF MAKING UPSET SEAMLESS TUBING Filed Nov. 7, 1938 3 Sheets-Sheetl 3 3 a INVENTOR.

wlmzssss BY 'LZM ,N-IZJ I 9'- ATTORNEYS.

May 6, 1941- s. E. DIESCHE R METHOD OF MAKING UPSET SEAMLESS TUBING FildNov. '7, 1938 a Sheets-Sheet 2 INVENTOR. 1

z, ATTORNEYS.

5 Sheets-She t 5 Filed Nov. 7, 193

INVENTOR 1%; ATTORNEYS.

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ww N Q :1 mm. m m\ 2 fimwuwgggag E255 Patented May 6, 1941 METHOD OFMAKING UPSET SEAMLESS TUBING Samuel E. Diescher, Pittsburgh, Pa.,assignor to Diesclier Tube Mills, Inc Pittsburgh, corporation of DelawarPa., a

Application November 1938, Serial No. 239,211

7 Claims;

This invention relates to the manufacture of seamless tubing having oneor more portions of it provided with a wall thickness greater thannormal, or; in other words, having what is conventionally known as oneor more upsets.

is first heated and then subjected in suitable dies to compression in adirection parallel to the axis of the tube to upset or thicken themetaL' This is a hot work operation that is performed subsequent to theproduction of tubes, and accordingly adds materially to their cost ofmanufacture. Furthermore, in such operations it is, difflcult, if

not impossible, so to upset the ends of tubes that the transition fromthe thickened to the normal wall is of a sufficiently gradual slopefully to meet many requirements of service. when conventionally formedupset tubing is subjected to vibration it is liable to break in theregion of its transition from its upset to its normal wall thickness byreason of the lnsuilicient slope of wall thickness in such region. Also,the upsets that can readily be formed in the conventional manner justexplained are so limited in length that the upset ends of the tubescannot be repeatedly cut back for rethreading, as is frequentlydesirable in the repeated use of oil and gas country goods. For longerupsets or upsets made in lighter wall product more than one suchupsetting operation is required, and, in the lightest wall product thatcan be made by hot work- For example,

mandrel which introduces a time consuming additional and costlyoperation.

The objects of the present invention are to provide a method ofmanufacturing upset seamless tubing in which the upsets can be made ofany desired length, at the ends or in any desired positions throughoutthe length of the tubing, with any desired slope in the transition fromthe upsets to the normal wall thickness, and without performing anymanufacturing step in additionto those required for the production oftubin having uniform wall thickness from endto end except when thetubing is produced with relati'vely. thick upsets. l

In my United States Patent No. 1,870,209 there is disclosed a method ofreducing the wall thickness and elongating a tubular blank, according towhich, in the manner therein specifically disclosed, a tubular blank orwork piece iscrossing, upsetting by the usual method may be regarded asbeing commerciallyimpossibie.

While upset tubing is now made in the manner just explained, the priorart contains several 'sug. gestions that upsets be formed in the courseof production of tubing, and particularly in the manufacture of seamlesstubing by the swaging process. According tothese suggestions, swagingmandrels are provided with portions which are of smaller than normaldiameter and on rolled on a cylindrical mandrel of the same crosssection throughout its working extent. The helicaliy acting cross-rollsuniformly reduce the wall thickness of the blank and cause it to bulgelaterally away from the mandrel between such rolls, and feed the blankand the mandrel forward. Between the cross-rolls the lateral bulging ofthe blank is limited, the peripheral flow of the metal is divertedlongitudinally, and the metal of the blank is pulled forwardly by a pairof guide discs that are driven at a peripheral speed in excess of thespeed of longitudinal movement of the blank effected by the cross-rolls.

My present invention is predicated primarily upon my discovery that itsstated objects can be attained during the elongating and wall reducingof tubular blanks according to the method of my aforesaid patent byeifecting the cross-rolling on a mandrel which has a normal-diametercylindrical portion for determining the normal wall thickness of theelongatedtubing, and which has a smaller-diameter portion for producingan upset, or, in other words, a greater than normal wall thickness. 1have found that by properly which upsets or thickened portions areswaged. 1

Because such tubes are formed in closed passes the'y'stick tightly uponthe mandrels. This requires the upsetting to be performed in stages,each preceded by a partialextraction of the coordinating controllableelements and factors of the mill and method disclosed in my aforesaidpatentpa seamless tube canbe provided with normal upsets at one or bothof its ends and also at any desired intermediate point or pointsthroughout its length without performing any operation in addition tothose required for the "production of a like tube of uniform wallthickness from end to end. When itis desired to similarly provide a;tube with one or more relatively thick, as distinguished from normal,upsets an additional procedural stepof a simple the elements of the millbeing formed and coordinated to elongate a tubular blank andsimultaneously to provide its ends with upsets;

Fig. 2 a central sectional view through a mandrel stripper in theoperation of removing a mandrel from a tube after the completion of anelongating operation in which the ends of the tube have simultaneouslybeen provided with normal upsets; Fig. 3 a view similar to Fig. 2showing the stripper in the operation of removing a mandrel on which atube has been elongated and simultaneously provided with normal upsetsintermediate of its ends; Fig. 4 a vertical longitudinal central view ofan apparatus for removing a mandrel from a tube that has been elongatedand simultaneously provided with relatively thick end upsets; Fig. 5 adetailed view partly 2,241,oss

I its forward end engages another removable stop in Fig. l, the workingelements of the mill having first been suitably adjusted to obtain thedesired result as will presently be explained. This in longitudinalcentral section, of the end of a specially formed mandrel; Fig. 6 alongitudinal Fig. 6; and Fig. 10 a vertical longitudinal centralsectional view of a reciprocating expander operating upon the end of atube initially provided with an interior upset.

In the practice of my invention in its applicability to the elongatingof tubular blanks and simultaneously providing them with normal endupsets, it is first necessary to provide suitable mill comprises a pairof oppositely disposed helically acting rolls 6, which may be of generalbarrel-shape type, as illustrated, although they may be of any otherdesired type or form such as conical or disc. When barrel-shaped crossrolls are used their axes are inclined to each other and to the line offeed of a blank between them. Disposed between the cross rolls, and onopposite sides of the pass between them, there are surfaces that bear onthe blank and move in the direction of its longitudinal extent. Thesesurfaces are preferably the grooved peripheries of a pair of guide discs'I which are driven at a peripheral speed materially in excess of thatof the longitudinal movement of the blank effected by the helicallyacting cross rolls. In adjusting the mill v the cross rolls are sopositioned laterally from the center line of the pass that at thethroat, or most distance from the mandrel in excess of the spacmandrels,such as illustrated in Fig. 2. Each such mandrel has a normal-diametercylindrical portion 2 which cooperates with helically acting re ducingrolls to determine the normal wall thickness of the-resultant tube, andis provided at its front and rear ends with smaller-diameter portions 3and .4, respectively, which similarly cooperate with suchrolls toproduce upsets at the ends of tubes. preferred to have the rearsmall-diameter portion 4 of greaterlength than the forward portion 3.Between its end and intermediate portions the mandrel is provided withtapered sections 0, the extent of which is determined largely from theslope of transition that is desired from the upsets Although it is notessential, it is to the normal wall thickness of a tube. This specialforming of mandrels involves merely a machining. operation that addslittle, if any, to the cost of production of the tubes.

A' mandrel such as just described is placed within a thick-wall tubularblank which may be, and preferably" is, produced by piercinga solidbillet, although other tubular blanks, may

- be used. Because the extent or the forward end upset of an elongatedtube depends upon the length of the forward end of the blank that isreduced between the cross and the smallerdiameter portion 3 of themandrel, it is desirable definitely to position the end of the mandrelwith ing of the cross rolls. In thus positioning the guide discs, dueconsideration must be given to preserving their functions of divertinglongitudinally the peripheral flow of the metal, limiting the bulging ofthe blank between the cross rolls and away from the mandrel, and pullingthe blank forward in the pass.

With the cross rolls and guide discs thus p0sitioned, and with theforward ends of the blank and mandrel relatively positioned in themanner explained above, the blank and mandrel are fed forwardly in theline ofpass of the mill until the front end of the mandrel is in thepass and the front endof the blank is engaged by the cross rolls. Thewall thickness of the forward end of the blank is first reduced betweenthe cross rolls and the front smaller-,diameter'portion j of the mandrelto determine the wall thickness of the forward end upset ofthe'resulting; tube. As the operation proceeds, the cross rolls ,actsuccessively upon the portion of the blank between them and the taperedsection 5 to determine the slope of transition from the upset to thenormal wall 'thickness, then upon the portion of the blank section I ofthe mandrel to determine the slope of and moving the mandrel through theblank until transition, and finally'upon the portion of the blankbetween themand the rear smalldiameter portion A .of the mandrel. todetermine the rear end unfit. As shown In Fig. 2, the tube has a forwardend upset ll, an intermediate portion H of rior'msl'wall thickness, arear end upset l2, and sloping transition sections it and which aredriven at such peripheral speed that the elongated portion of the tubemoves longitudinally at a more rapid rate than does the' mandrel.Accordingly, at the end of a tube forming operation the forward end ofthe mandrel normally lies within the forward end of the tube, as shownin Fig. 2. This increase of rate of longitudinal movement of the forwardend of the tube is effected primarily during the elongation of thenormal wall portion of the tube because of the greater reduction in wallthickness then being made, there being less and in some cases nodifferences, in rate of movements during the formation of the upsets land [2. Because ofv this and of the ovality created while being rolledthere is no binding of therear upset end I2 of the tube upon the mandrelwhile it is being formed, regardless of the wall thickness of suchupset; Should the upset be of normal thickness the ovality created inthe rolling thereof will suflice to provide clearance between the boreof practice of my invention in elongating tubular the upset and the bodyof themandrel and thus avoid any possibility of binding, and should theupset be of heavy thickness there will be so little difference betweenthe forward speed of the mandrel and of the upset portion as to permitwhat ovality that does occur to suffice for the little forward clearancethat may be needed.

An important factor involved in the forming of normal upsets in thepractice of this invention is that the relative spacings of the guidediscs and of the cross rolls, and the relation between the diameters ofthe normal-diameter portion 2 and the smaller-diameter end portions 3and l of the mandrel are such that the interior circumference of theupsets is greater than the circumference of the normal-diameter portionof the mandrel. The result of this coordination of the several elementsof the mill is that the mandrel can be freely removed from the formedtube. This may be done in the manner illustrated in Fig. 2 byengagingthe rear end of the mandrel between a pair of yieldingly mountedpinch rolls l5 which are driven to move the mandrel outwardly, and byabutting the end of the tube against a stripping collar l6. This mandrelextractor is used in removing mandrels from tubes having uniform wallthickness from end to end when they are produced according to the methoddisclosed in my aforesaid Patent No. 1,870,209. Accordingly, in thepractice of my present invention seamless tubes having normal endinterior upsets are produced without any procedural step in addition tothose required in a production'of such tubing having uniformwallthickness from end to end. Reference has been made to the difference inrate of longitudinal movements from the forward end of a tube and amandrel on which it is formed. This difference in rate is substantiallyuniform for a given setting and driving of the mill and for a givenmandrel size when used to produce end upset tubing from tubular blanksof uniform size. Accordingly, successively formed tubes have their endupsets uniformly spaced' apart.

By way of example, and not of limitation, the following specific dataare given to illustrate the construction and positioning of millelements, including the mandrel, that may be used in the blanks andsimultaneously providing them with normal end upsets in the mannerexplained above. The mandrel may have a normal diameter portion 20 feet6 inches in length and 2.41 inches in diameter, and have at each end,beyond its 20 feet 6 inches normal diameter portion, a reduced portionof 2.19 inches in diameter, and the tubular pierced blanks may have anoutside diameter of 31% inches, a wall thickness of 0.38 of an inch, andmay be 14 feet! inches long. With the cross rolls spaced 2.78 inchesfrom each other at the throat of the pass, and the bottoms of theperipheral grooves of the guide discs spaced 3.10 inches from each otherat the throat of the pass, the blanks will become elongated to tubesapproximately 30 feet long, 3 inches outside diameter from end to end,0185 of an inch normal wall thickness, and 0.295 of an inch wallthickness at the upset ends. The interior circumference of the endupsets will be greater than the circumference of the normaldiameterportion of the mandrel, so that the resulting tubes can readily bestripped from the mandrel in the manner shown in Fig. 2.

In the practice of the invention, tubes may be provided with one or moreinterior upsets intermediate of their ends by following the sameprocedure that has thus far been explained, except for the constructionof the mandrel, which, as shown in Fig. 3, is formed to have a pluralityof normal-diameter portions 20 at its ends and intermediate thereof, anda plurality of small diameter portions 2| intermediate of its ends.

Tubes elongated on such mandrels have normal successfully used in thepractice of my invention in elongating tubular blanks and simultaneouslyproviding them with normal intermediate upsets of the characterillustrated in Fig. 3. The mandrel has a normalediameter portion 1.70inches in diameter, and six smaller-diameter portions 1.56 inches indiameter. The tubular pierced blanks were 103.5 inchesin length havingan outside diameter of 2% inches and a wall thickness of 0.295 of aninch. -These blanks were elongated and sized into tubes averaging 14feet 3 inches in length having an outside diameter of 2.35 inches,'anormal wall thickness of 0.20 of an inch, and internal upsets of 0.27 ofan inch. in thickness. In making the upset tubes just described the mainor cross rolls were spaced 2.10 inches and the guide discs 2.37 inchesapart.

Tubes having upsets intermediate of their ends may advantageously beused in the manufacture of upset tubular articles in multiples, whereinthe upsets are located at points where greater strength is required.Such tubes may be provided with an upset at one or both of their ends,.

and, in the production of tubes having no intermediate upsets, upsetsmay be formed at only one of their ends if desired.

By way of further example and not of limitation, the following specificdata are given toillustrate the construction and positioning of millelements, including the mandrel, that have been used in the practice ofmy invention in elongating tubular blanks and simultaneously providingthem with very long end upsets as well as very long intermediate upsets.The mandrel had a normal diameter of 1.590 inches. It was turned down to1.470 inches at the ends, as well as at two stations therebetween, in amanner as to provide three portions of the mandrel, each 24 /2 incheslong, of normal diameter, and intermediate of these to provide twoportions, each 22 inches long of reduced diameter, namely 1.470 inches.The intermediate tapers 'were 1.00 inch long. On this mandrel tubes 2inches in diameter and 16 feet 1 inch long were rolled, having 0.240inch of wall at 20 inches of length at their two end upsets and also at27 inches of length at their two intermediate upsets. The threeremaining portions, intermediate of the upsets, were each 33 inches longand were of0.l87 inch, or of normal wall thickness except at thetransition tapers. These articles were rolled with the same ease aswould have been the case were the mandrel of uniform diameter and theproduct of uniform wall thickness. In this case the main rolls werespaced 1.964 inches apart and the guide discs were 2.25 inches apart.The pierced shells used were 2.50 inches in diameter, 0.325 inch in wallthickness and 105 inches long.

The invention has been thus far explained in its applicability to theproduction of tubing having end and intermediate upsets of ,a normalcharacter, as distinguished from relatively thick upset which aresometimes required. In the practice of my invention one or both ends oftubes maybe provided with relatively thick upsets with no change in theelongating procedure except that the smaller-diameter end portions ofthe mandrels are, with the relation to their normal-diameter portions,reduced more in size than in mandrels used for producing normal upsets.One difierence between an elongated tube provided at both ends withrelatively thick rather than normal upsets is that in the former theinterior circumferences of the upsets are smaller than thenormal-diameter portion of the mandrels, as a result of which themandrel on which each tube is formed is entrapped by the upsets. Anotherdifference is that the outside diameter of relatively thick upset endsis slightly less than that of the normal wall thickness portion of thetube. This second difference arises from the fact that in the productionof relatively thick end upsets the relatively small reduction in wallthickness of the portions of the tubular blank that form the upsets doesnot cause the metal to bulge laterally or oval against the guide discsto an extent sufficient to expand the circumference of the upsets tothat of the normal wall thickness portion of the blank which is given amaterially greater reduction by the cross rolls.

To remove a thus entrapped mandrel from a tube that has been providedwith relatively thick and upsets, it is preferable to use a pushermechanism, such as illustrated in Fig. 4, than the pinch rolls of Figs.2 and 3, because a greater and more positive force can be applied by thepusher mechanism. As shown in Fig. 4, the pusher comprises a ram 25attached to a crosshead 26 which is connected to the end of a piston rod21 adapted to be reciprocated by a compressed air or other form ofpressure fluid cylinder 28. In removing a mandrel by t s pusher, theforward end of ram 25 may be centered in 2,241,,ces

the trailing end of the mandrel which projects from a finished tube, andthe fluid pressure cylinder actuated to push the mandrel out of thetube, the end of which is engaged by a stripping collar 29. During thisoperation the upset at the end of. the tube, which at this stage isstill .hot and readily deformable and which abuts against collar 29, isexpanded by the tapered section of the mandrel between its normal. andsmaller-diameter portions. This leaves the outside diameters of theupsets of diflerent size, the upset through which the mandrel has beenremoved being larger than that at the other end of the tube. However,this difference in the outside diameters of the upsets, and thedifierence, explained above, between the outside diameters of the upsetsand normal wall portion of the tube, are not prejudicial because thetube may readily be brought to uniform diameter from end to end bypassing it through sizing rolls or a sink mill as is customarily donesubsequent to the production of tubes having uniform wall thicknessthroughout.

If at the completion of the mandrel-removing operation it is desired tohave both of the end upsets of the same diameter, the pusher may begiven a short stroke suflicient only to cause the mandrel to expand oneupset, and the tube and its contained mandrel may thenbe transferredlaterally to position it in line with a second similar pusher mechanismconstructed to engage the other end of the mandrel and push it throughthe previously unexpanded upset and entirely out of the tube. Ifdesired, the tube may then be passed through a sizing or sink mill asexplained above, or its upset ends may be further expanded in a mannerhereinafter described, or it may be treated in any other desired way.

To resist wear on the tapered sections of a mandrel while it is moved inthe manner just explained to expand relatively thick upsets in theremoval of the mandrel from tubes, such sections may, as shown in Fig.5, be provided with heat and wear-resisting collars 30. When thus,formed, the normal-diameter portion of the mandrel may consist of acylindrical rod 3|, and each smaller-diameter end portion may consist ofa short rod 32 provided with an offset 33 to receive a collar 3%) andwith a threaded end 34 adapted to be screwed into the end of rod 3|.

Althoughthe production of tubes having relatively thick upsets requiresa manufacturing step or steps inaddition to those required for theproduction of tubing having uniform wall thickness from end to end,nevertheless no loss of operating time occurs because the additionalstep or steps are performed immediately after the elongating of eachupset tube and in less time than required for the elongation.

In providing tubes with upsets according to this invention, all theupsets are initially of the interior type, by which is meant that theincreased wall thickness of the upsets contracts the bore of the normalwall thickness portion of the tube. However, the interior upset ends ofthe tube can readily be converted into exterior upsets by merelyexpanding the ends, whether the upsets are of the normal or therelatively thick type. While in some cases this may b done on theoriginal heat of the metal, to prevent the metal from becoming too coolto be readily expanded without impairing it, the tubes may, in theirpassage from the mandrel extractor to the expander, be passed through aheating furnace.

Both upset ends of a tube may be simultaneously expanded by a rotaryexpander such as length of the'tube will be seamless tubes duringtheirregular course of illustrated in Fig. 6. To do this the ends of a heatedtube. and their intermediate portions as far as may be necessary, areengaged by clamps 40 which hold them in alignment'with spinning heads4|, each of which is attached to or is formed on the end of a spindle 42adapted to be rotated'by a motor 43. As shown particularly in Figs. 8and 9, spinning head M has a frustrum-like portion 44 which effects theexpanding of an upset and a cylindrical portion 45 which removes anyscores that may occur during such expanding. Spindle 42 is providedcentrally with a bore 46 which is closed at its outer end and throughwhich, and radial spindle ports 41, steam or a combustible gas orlubricant is led to the face of the spindle to facilitate the spinningor expanding operation and to cool thespinning tool and also to removescale that may accumulate at the tool. The spinning tool and its drivingmotor are mounted upon a table 50.

which is slidably supported on a platen and is engaged by a feed screw52 rotatably mounted on the platen and adapted to be driven by a motor53 through a worm shaft 54 and a worm gear 55. The platen 5| is slidablymounted upon a table 56 to properly position the spinning tool foroperation upon tubes of different lengths. As the spinning head 4| isrotated by the motor 43, screw 52 is driven by motor 53 to feed the headthrough the upset end of the tube until the entire upset, including theadjoining transition portion of the tube, is so expanded that its insidediameter is the same'as that of the main or normal wall portion of thetube.

In Fig. 10 there is illustrated an alternative form of expandingapparatus in which a nonrotatable expanding tool 60 is attached to theend of a spindle 6| adapted to be reciprocated by a compressed air orother form of fluid pressure cylinder 52. In Fig. '7 there is shown atube 65 provided with an end exterior upset 65 which may be either ofthe normal or relatively thick type, the upset having been thrown to theexterior of the tube by expanding an interior upset in the mannerexplained with reference to Figs. 6 and 10. r i

A specificexample of tubes requiring exterior end upsets is oil countrypump tubing having a 2-inch nominal inside diameter from end to end, anormal wall thickness of 0.19 of an inch, and

an upset end wall thickness of 0.30 of an inch,

and being 2% inches in outside diameter. Such a-tube may be formed fromthat produced in the first of the above explained examples, the tubewhen elongated bein'gappro'ximately feet in length and 3 inches inoutside diameter, and being provided with normal interior upsets at itsends. After being elongated the tube may be passed through a sink millto reduce its outside diameter to that required, namely 2% inches. Inits passage through the sink mill the increased in excess of 33 feet,and its wall thickness will be increased somewhat throughout butespecially at its ends, resulting in a tube having a normal wallthickness of 0.19.0f an inch, an upset end wall thickness of 0.30 of aninch, and an interior diameter of 2 inches throughout its normal wallportion. The upset ends of the tube may then be expanded in the mannerexplained with reference to either Fig. 6 or 10 to produce the requiredexterior upsets.

Many of the advantages of my invention are apparentfrom its foregoingdescription. In the first place, by its practice upsetsare-formed onmanufacture, rather than subsequent thereto, and they are iormed withoutany procedural step in addition tothose. used in the production ofseamless tubes having uniform wall thickness from end to end. The resultof this is a very substantialsaving in thecost of manufacture of upsettubing; In all cases the upsets may be of any desired length and theslopes of transition in wall thickness of the tube from their upsets totheir normal thickness walls may be as gradual as desired for anypurpose. Thus the upset ends of tubes may be cutback for rethreading, asis frequently done particularly in oil country tubing, and theresistance of .the tubes to breakage-in their transition sections isgreatly increased. Moreover, as the entire procedure involved in theproduction of upset tubing may be carried out rapidly enough to maintainthe entire tube at working temperature during its deformative period,the subsequent cooling of the tube occurs uniformly and as a consequencethe tube assumes a normalized condition.

A further advantage of the invention as compared to prior artsuggestions that upsets be formed in the course of production of tubingis that the tubes are formed in open passes, by which is meant that theyare formed in passes which free the tubes from rather than cause them tobe formed tightly uponthe mandrels. The result of this is thatadditional steps are not required to free the formed tubes from themandrels.

A still further advantage of my invention is that it may be practiced inthe production of very thin wall tubing which in its finished form isnot provided with upsets. In the hot production of the very thin walltubing that can be made according to the method disclosed in myaforesaid Patent No. 1,870,209, as, for example, of an inch in wallthickness, the trailing ends of the tubes sometimes become slightly tornand injure the highly finished surfaces of the guide discs,necessitating the substitution of new discs and the refinishing ofthosewhose peripheral faces have been thus marred. By providing the endsof such thin wall tubing with relatively it. However, I desire to'haveit understood that.

within the scope of the appended claims, the invention maybepracticedotherwise than specifically disclosed. a I claim:

1. The method ofelongating a heated tubular blank and simultaneouslyreducing its wall principally to a normal and;locally to an upsetthickness, which comprises cross-rolling the blank continuously from endto end between helically acting reducing rolls and can longitudinallymoving mandrel having a normal-diameter cylindrical portioncooperating'withthe reducingr olls for determining said normal wallthickness and having a smaller-diameter portion for producing said upsetwall thickness, and determining theouterdiameter ofthe formed tube by.surfaces bearing on the blank and moving in the direction of itslongitudinal movement.

2. The method of elongating a heated tubular blank and simultaneouslyreducing its Wall principally to a normal and locally to an upsetthickness, which comprises cross-rolling the blank continuously from endto end between helically acting reducing rolls and on a longitudinallymoving mandrel having a normal-diameter cylindrbcal portion cooperatingwith the reducing rolls for determining said normal wall thickness andhaving a smaller diameter portion cooperating with the reducing rollsfor determining said upset wall thickness, and determining the outerdiameter of the formed tube by surfaces bearing on the blank and movingin the direction of the longitudinal movement of the blank at a speedgreater than the longitudinal movement of the blank.

3. The method of elongating a heated tubular blank and simultaneouslyreducing its wall at its ends to an upset thickness and throughout itsintermediate portion to a normal smaller thickness, which comprisescross-rolling the blank continuously from end to end between helicallyacting reducing rolls and on a longitudinally moving mandrel having anintermediate normaldiameter cylindrical portion cooperating with thereducing rolls for determining said normal wall thickness and havingsmaller diameter end portions for producing said end upset wallthickness, and determiningthe outer diameter of the formed tube bysurfaces bearing on the blank and moving in the direction of itslongitudinal movement.

- 4. The method of elongating a heated tubular blank and simultaneouslyreducing its wall principally to a normal and locally to an internalupset thickness, which comprises cross-rolling the blank continuouslyfrom end to end on a mandrel moving longitudinally between helicallyacting reducing rolls and between rotating guide discs, the mandrelhaving a normal-diameter cylindrical portion for determining said normalwall thickness and having a smaller diameter portion for determiningsaid upset wall thickness, causing the cross-rolls to compress the blankbetween them and the mandrel at both its normal and smaller diameterportions and to so expand the blank from the mandrel and against theguide discs that the interior circumference of the inwardly upsetportion of the blank is greater than the exterior circumference of thenormal diameter portion of the mandrel, and causing the guide discs topull the blank forwardly, whereby the upset thickened wall portion ofthe blank may freely pass over the normal diameter portion of themandrel.

5. The method of elongating a heated tubular blank and simultaneouslyreducing its wall at its ends to an upset thickness and throughout itsintermediate portion to a normal smaller thickness, which comprisescross-rolling the blank continuously from end to end on a mandrel movinglongitudinally between helically acting reducing rolls and betweenrotating guide discs, the mandrel having an intermediate normal-diametercylindrical portion for determining said normal wall thickness andhaving smaller diameter end portions for determining said end upset wallthickness, causing the cross-rolls to compress the blank between themand the mandrel at both its end and intermediate portions and to soexpand the blank from the mandrel and against the guide discs that theinterior circumference of the inwardly upset end portions of the blankis greater than the exterior circumference of the normal diameterintermediate portion of the mandrel, and causing the guide discs to pullthe blank forwardly, whereby the 'upset end portions of the blank mayfreely pass over the intermediate portion of the mandrel.

6. The method'of elongating a heated tubular blank and simultaneouslyreducing its wall at its ends to an inwardly upset thickness andthroughout its intermediate portion to a normal smaller thickness, whichcomprises cross-rolling the blank continuously from end to end on amandrel moving longitudinally between helically acting reducing rollsand between rotating guide discs, the mandrel having an intermediatenormal diameter portion for determining said normal wall thickness andhaving smaller diameter end portions for determining said end upset wallthickness, causing the cross-rolls to compress the blank between themand the mandrel at both its end and intermediate portions and to soexpand the blank from the mandrel and against the guide discs that theinterior circumference of the inwardly upset end portions of the blankis less than the exterior circumference of the normal diameterintermediate portion of the mandrel, causing the guide discs to pull theblank forwardly, and thereafter expanding the inwardly upset ends of theformed tube.

7. The method of elongating a heated tubular blank and simultaneouslyreducing its wall principally to a normal and at an end to an internalupset thickness, which comprises cross-rolling the blank on a mandrelmoving longitudinally between helically acting reducing rolls andbetween rotating guide discs, the mandrel having a normal-diametercylindrical portion for determining said normal wall thickness andhaving a smaller diameter end portion for determining said upset wallthickness, causing the cross-rolls to compress the blank between themand the mandrel at both its normal and smaller diameter portions and toso expand the blank from the mandrel and against the guide discs thatthe interior circumference of the inwardlyupset portion of the blank issmaller than the exterior circumference of the normal diameter portionof the mandrel,

and thereafter expanding the inwardly upset portion of the formed tubeby moving the normal diameter portion of the mandrel into such upsetportion.

SAMUEL E. DIESCHER.

